Sealing device

ABSTRACT

A double acting sealing assembly including a modified T-shaped sealing ring and mating substantially trapezoidal shaped back-up rings or anti-extrusion rings are provided. An annular void is provided at the static surface of the sealing ring. The sealing surface of the ring is formed by converging end faces which meet at a sharp sealing edge. In an alternative embodiment, the void may be filled with a material different from that of the sealing ring.

United States Patent [191 Burke Nov. 13, 1973 SEALING DEVICE 2,765,20410/1956 Josephson 277/188 [75] Inventor: John A. Burke, Rocky River,Ohio Primary ExaminerGeorge E. Lowrance [73] Assignee: Greene, Tweed &Co., Inc., North Assistant Examiner Robert Smith wales Attorney-ArthurH. Seidel et a1.

[22] Filed: June 5, 1972 211 Appl. No.: 259,640 [571 ABSTRACT A doubleacting sealing assembly including a modified [52] U 8 Cl 277/188 277/165T-shaped sealing ring and mating substantially trape- [51] Int. Cl i15/24 zoidal shaped back-up rings or anti-extrusion rings are [58] Fieldl 189 165 provided. An annular void is provided at the static surface ofthe sealing ring. The sealing surface of the ring [56] References Citedis formed by converging end faces which meet at a sharp sealing edge. Inan alternative embodiment, the UNITED STATES PATENTS void may be filledwith a material different from that 3,473,814 10/1969 Bastow 277/188 f hli i 3,614,114 10/1971 Traub 3,630,485 12/1971 Williams 277/188 8Claims, 5 Drawing Figures SEALING DEVICE This invention is directed to adouble acting sealing device which is particularly designed for use inhydraulic or pneumatic systems such as linear actuators or the brakecylinder for an aircraft wheel system. The sealing ring of the presentinvention has a sealing edge designed in a manner so that the sealingassembly results in a dry rod or bore condition while being lesssusceptible to compression-set behavior. A seal is attained due to thestructural relationship of the sealing device with minimal squeeze whilethedevice is resistant to surface tearing under very high pressures andextrusion gap conditions.

The sealing ring is generally T-shaped in section with axially directedlegs at the static face. The side faces of the ring converge upwardlyfrom the legs. Sealing rings of this nature are known as per U.S. Pats.Nos. 3,6l4,l l4 and 2,765,204. The sealing ring of this inventionconstricts the upwardly converging side faces so that they terminate inconverging end faces meeting at a sharp dynamic sealing edge.

The sealing ring is provided with complementary back-up oranti-extrusion rings which are generally trapezoidal in section. Thedesign objective of the invention is to have converging side faces toeffect a gain in the outward thrust of the back-up or anti-extrusionrings by a vector force such as a wedge. Further, the trapezoidal shapeof the back-up or anti-extrusion rings tends to key the parts togetherlessening the chance of misassembly or misalignment under shock andspike pressurizations. All inside corners of the ring except for thesharp lip are rounded or filleted to eliminate abrupt changes in crosssection that could result in stress-risers or potential overstressfailure.

It is an object of the present invention to provide a novel compressionsealing device.

It is another object of the present invention to provide a sealingdevice which is efficient, long-lasting, and less susceptible tocompression-set deficiency.

It is another object of the present invention to provide a sealingdevice which will effect a seal with minimum squeeze while beingresistant to surface tearing or abrading under very high pressure andextrusion gap conditions.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there is shown in thedrawings a form which is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 is an end elevation view of the sealing ring.

FIG. 2 is a side elevation view of the sealing ring shown in FIG. 1.

FIG. 3 is a sectional view of the sealing ring on a large scale takenalong the line 3-3 in FIG. 2.

FIG. 4 is a sectional view showing the sealing ring mounted in its glandwith its trapezoidal back-up or anti-extrusion rings to effect a sealwhile being illustrated on an enlarged scale.

FIG. 5 is a sectional view similar to FIG. 4, but illustrating anotherembodiment of the present invention.

Referring to the drawing in detail, wherein like nu- I merals indicatelike elements, there is'shown in FIGS. 1 and 2 a sealing ring inaccordance with the present invention designated generally as 10. Thesealing ring is annular and is provided either on its outer or innerperipheral surface with a sharp sealing edge 12. When the sealing ringis to be mounted in a groove of a bore and is intended to effect a sealwith a rod extending through the bore, the sealing edge would be on theinner periphery of the ring. When the sealing ring is to be mounted on amoving rod or piston and adapted to effect a seal with the bore, theedge 12 is on the outer periphery of the ring.

The ring 10 is generally T-shaped in section. The sealing edge 12 isdefined by the intersection of flat converging end faces 14 and 16disposed at an angle of about 16 to 22 with respect to the axis of thering 10. The ring 10 includes converging side faces 17 and 18 whichextend to the end faces 14 and 17 from axially extending legs 20 and 22.

For purposes of illustration, the ring 10 has its sealing edge 12 on itsouter peripheral surface. The legs 20 and 22 define the width of thering and also define the inner peripheral surface 26. Centrally disposedon the inner peripheral surface 26, opposite the sealing edge 12, thereis provided a void 24. Void 24 is attained by providing a groove in thesurface 26. Depending upon the function of the ring 10 as describedabove, the void 24 is on the inner or peripheral surface of the ring butalways opposite the lip 12.

The ring 10 is provided with back-up or antiextrusion rings 28 and 30which are complementary to the side faces 17 and 18 and the legs 20 and22. See FIG. 4. The height of the rings 28 and 30 correspondsapproximately to the height of the converging walls 17 and 18.

As illustrated in FIG. 4, the sealing device is mounted in a groove 32on the first member 34. The sealing edge 12 contacts the second member36 whereby a seal is effected between members 34 and 36. Either one ofmembers 34, 36 may be a movable member. Under static conditions therings 28 and 30 do not form a seal with either of members 34 and 36.Under pressurized conditions, the void 24 provides a gap into which thering 10 may deform, allowing edge 12 to remain defined rather than beingflattened under compressive forces resulting in a wiping action on thesurface of member 36, thereby effecting a more perfect dynamic sealingfunction. i

The ring 10 may be made from a wide variety of polymeric plasticmaterials such as nitrile rubber, carboxylated nitrile rubber, afluorinated elastomer such as Viton (Trademark), etc. The anti-extrusionrings 28 and 30 are preferably low friction members made from a bearingmaterial such as wear resistant nylon, Teflon (Trademark), or mixturesthereof.

In FIG. 5, there is illustrated another embodiment of the presentinvention designated generally as 10'. In FIG. 5, the correspondingelements are provided with corresponding primed numerals. The device inFIG. 5 is the same as the device described above except as will be madeclear hereinafter.

In FIG. 5, the ring is provided with a void 24' which is substantiallygreater than the void 24. Thus, as shown more clearly in FIG. 4, thevoid 24 had a depth equivalent to about two-thirds the thickness of thelegs 20 and 22. In FIG. 5, the depth of the void 24' is approximatelypercent of the radial thickness of the ring.

The void 24 is filled with a core 38. The core 38 is an elastomericmaterialdifferent from the material of the sealing ring and hasproperties whereby it is substantially more flexible and easier todeform, retaining its elasticity at greater temperature variables.Suitable materials for the core 38 include silicone rubber,fluorosilicone rubber, etc., when using the materials described abovefor the sealing ring. A wide variety of other soft and/or easilydeformable polymeric plastic materials may be utilized for the core 38.

In the embodiment shown in FIG. 5, the sealing ring is preferably anelastomer selected so as to attain the greatest compliance andadaptability to specific environmental conditions while performing itsfunction to seal the dynamic surface and energize the back-up oranti-extrusion rings. The core 38 is separately molded of a differentelastomeric material selected to provide the desirable propertieswhereby it will provide optimum resilience to maintain constant contactbetween the ring and groove under all service conditions while providingthe static scaling function.

Generally T-shaped sealing rings have been proposed heretofore. In thepresent invention, it is particularly significant that the ring has asharp sealing edge 12 defined by converging end faces 14 and 17 with theconverging side faces 16 and 18 extending from the axially disposed legs20 and 22. As a result of the structural interrelationship, a wedgingaction under dynamic conditions can be attained so that a suitable sealunder high pressure and extrusion gap conditions may be attained withlong life for the entire sealing device. I have found that a sharpsealing edge performs better than a flat or rounded sealing edge whichtend to be nibbed away thereby inducing seal failure.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification as indicating the scope of theinvention.

I claim:

1. A sealing device comprising an annular T-shaped cross-section sealingring of elastomeric material, said ring having axially extending legsand convering side faces merging into converging end faces, said endfaces meeting to define a sharp sealing edge, a complementary matinganti-extrusion ring juxtaposed to each side face and the adjacent leg,said anti-extrusion rings being generally trapezoidal in section andhave a radial dimension corresponding generally to but not substantiallygreater than the height of said converging side faces, and said sealingring having a void on the peripheral surface opposite said sealing edge.

2. A sealing device in accordance with claim 1 wherein said void isshallower than the thickness of said legs.

3. A sealing device in accordance with claim 1 wherein said void isdeeper than the thickness of said legs.

4. A sealing device in accordance with claim 3 including a core in saidvoid, said core being made from a material which is of a differenthardness than the material of said sealing ring.

5. A sealing device in accordance with claim 1 wherein said sealing ringis a nitrile rubber, and said anti-extrusion rings being made from amaterial which is self-lubricating.

6. Apparatus comprising a sealing device for sealing the annularclearance between opposed surfaces on first and second interfittingmembers, said first member having an annular groove receiving saidsealing device, said second member having a cylindrical surface opposedto said groove, said sealing device including an annular T-shapedcross-section sealing ring of elastomeric material, said ring havingaxially extending legs and converging side faces merging into convergingend faces, said end faces meeting to define a centrally disposed sharpsealing edge in contact with said cylindrical surface, a complementarymating anti-extrusion ring juxtaposed to each side face and the adjacentleg, and said sealing ring having a void on the peripheral surfacethereof which is juxtaposed to the groove and opposite the peripheralsurface containing said sealing edge.

7. Apparatus in accordance with claim 6 wherein each anti-extrusion ringhas a height corresponding to the distance between said legs and theintersection of a side face with the end face so as to be spaced fromsaid second member under static conditions.

8. Apparatus in accordance with claim 6 wherein each anti-extrusion ringis in sealing contact with a side face of said sealing ring and a sidewall of said groove.

1. A sealing device comprising an annular T-shaped cross-section sealingring of elastomeric material, said ring having axially extending legsand convering side faces merging into converging end faces, said endfaces meeting to define a sharp sealing edge, a complementary matinganti-extrusion ring juxtaposed to each side face and the adjacent leg,said anti-extrusion rings being generally trapezoidal in section andhave a radial dimension corresponding generally to but not substantiallygreater than the height of said converging side faces, and said sealingring having a void on the peripheral surface opposite said sealing edge.2. A sealing device in accordance with claim 1 wherein said void isshallower than the thickness of said legs.
 3. A sealing device inaccordance with claim 1 wherein said void is deeper than the thicknessof said legs.
 4. A sealing device in accordance with claim 3 including acore in said void, said core being made from a material which is of adifferent hardness than the material of said sealing ring.
 5. A sealingdevice in accordance with claim 1 wherein said sealing ring is a nitrilerubber, and said anti-extrusion rings being made from a material whichis self-lubricating.
 6. Apparatus comprising a sealing device forsealing the annular clearance between opposed surfaces on first andsecond interfitting members, said first member having an annular groovereceiving said sealing device, said second member having a cylindricalsurface opposed to said groove, said sealing device including an annularT-shaped cross-section sealing ring of elastomeric material, said ringhaving axially extending legs and converging side faces merging intoconverging end faces, said end faces meeting to define a centrallydisposed sharp sealing edge in contact with said cylindrical surface, acomplementary mating anti-extrusion ring juxtaposed to each side faceand the adjacent leg, and said sealing ring having a void on theperipheral surface thereof which is juxtaposed to the groove andopposite the peripheral surface containing said sealing edge. 7.Apparatus in accordance with claim 6 wherein each anti-extrusion ringhas a height corresponding to the distance between said legs and theintersection of a side face with the end face sO as to be spaced fromsaid second member under static conditions.
 8. Apparatus in accordancewith claim 6 wherein each anti-extrusion ring is in sealing contact witha side face of said sealing ring and a side wall of said groove.